Leonard [about his mother]: She's only been here a day and a half, and I'm seriously considering alcoholism as a new career path.
Penny: Hey, I talked to her for five minutes yesterday, and I've been half bombed ever since.

At that age, he was well enmeshed in what Freud would call the Phallic Stage of psycho-sexual development; an outmoded theory, of course, but the boy did spend most of his waking hours with a tight grasp on his penis

Mrs. Hofstadter [describing Leonard at age 6]

Penny: What was Leonard like when he was little?
Mrs. Hofstadter: Oh, I think you mean "young." He's always been little.

Penny [about his mom]: You can't let her get into your head
Leonard: It's too late for me, my head is her summer house

Mrs. Hofstadter [about Penny]: If you want to have sex with that woman, find out what kind of cologne her father wore
Leonard: Hello mother

The Big Bang Theory Season 2 Episode 15 Quotes

Penny [about his mom]: You can't let her get into your head
Leonard: It's too late for me, my head is her summer house

Mrs. Hofstadter [about Penny]: If you want to have sex with that woman, find out what kind of cologne her father wore
Leonard: Hello mother